1. Technical Field
The present disclosure relates to a fin tube heat exchanger used in a heat pump.
2. Description of the Related Art
Heat pumps typically include a compressor, a condenser, a decompressor, and an evaporator, which are connected in this sequence in a refrigerant circuit. The condenser and the evaporator may be fin tube heat exchangers. In such a case, the condenser and the evaporator each include a plurality of fins arranged at a predetermined interval and a heat transfer tube extending through the fins. Air flowing between the fins exchanges heat with a fluid flowing in the heat transfer tube.
Japanese Unexamined Patent Application Publication No. 2013-221682 discloses a fin of a fin tube heat exchanger. The fin has only one peak portion when viewed in an air flow direction. FIG. 1 is a plan view illustrating the fin.
In FIG. 1, an arrangement direction of the fins 31 is defined as a height direction Y, a direction parallel to a front edge 30a is defined as a row direction Z, and a direction perpendicular to both the height direction Y and the row direction Z is defined as an air flow direction X (flow direction of air A).
In FIG. 1, a ridge of a peak portion 34 extends in the row direction Z. The fin 31 is a corrugated fin. The fin 31 includes a flat portion 35, first inclined portions 36, and second inclined portions 38. The flat portion 35 is adjacent to a fin collar 37 and has a circular ring shape extending around a through hole 37h (see FIG. 3). The surface of the flat portion 35 extends in the air flow direction X, which is perpendicular to the height direction Y.
The first inclined portions 36 are inclined with respect to the air flow direction X so as to form the peak portion 34. The first inclined portions 36 occupy the largest area of the fin 31. The first inclined portions 36 are positioned on respective left and right sides of a reference line extending in the row direction Z through the center of a heat transfer tube 21. In other words, the first inclined portion 36 on a windward side and the first inclined portion 36 on a leeward side form the peak portion 34.
The second inclined portions 38 smoothly connect the flat portion 35 with the first inclined portions 36 so as to eliminate a difference in level between the flat portion 35 and the first inclined portions 36. The second inclined portions 38 each have a gently curved surface.
The fin 31 has only one pair of the first inclined portions 36 in the air flow direction X. The first and second inclined portions 36 and 38 monotonically increase in height toward a positive side (in a protrusion direction of the fin collar 37 in which the fin collar 37 protrudes from the flat portion 35 in the height direction Y) as a distance from a central plan Hc increases. This configuration reduces pressure loss of the airflow, and thus clogging due to frost is reduced.